muixirt: You're more than welcome to work on it if you'd like. I'd recommend you look at jnthn's 6model work. He's currently working on Parrot, JVM, and .Net backends, so you could certainly look at adding something you like better.

So you can't just use naive C stack frames, you instead have to do something like holding separate stack frame, lexpad, etc. structs somewhere else in memory, and have a separate bit of code that moves between them iteratively instead of recursively.